The proposed experiments are designed to define the effects of noise on interaural time discrimination. It has been demonstrated that midline interaural time discrimination, unlike detection threshold, is poorer when the signal is presented against a background of interaurally phase reversed white noise than when the background noise is diotic. This research proposal is directed toward determining if this poorer interaural time discrimination is due to the creation of a masking-level difference by the interaurally phase reversed noise, or if it is caused by some intrinsic characteristic of the interaurally phase reversed noise which interferes with interaural time discrimination. All data will be collected using an adaptive two-interval forced choice psychophysical procedure with feedback. It is expected that the results will clarify the nature of the relation of binaural detection threshold shifts to interaural time discrimination and also, will provide a description of the more general effect of noise on interaural time discrimination.